Probing the Crystal Structure Landscape by Doping: 4‐Bromo, 4‐Chloro,and 4‐Methylcinnamic Acids

Accessing the data points in the crystal structure landscape of a molecule is a challenging task, either experimentally or computationally. We have charted the crystal structure landscape of 4‐bromocinnamic acid (4BCA) experimentally and computationally: experimental doping is achieved with 4‐methylcinnamic acid (4MCA) to obtain new crystal structures; computational doping is performed with 4‐chlorocinnamic acid (4CCA) as a model system, because of the difficulties associated in parameterizing the Br atom. The landscape of 4CCA is explored experimentally in turn, also by doping it with 4MCA, and is found to bear a close resemblance to the landscape of 4BCA, justifying the ready miscibility of these two halogenated cinnamic acids to form solid solutions without any change in crystal structure. In effect, 4MCA, 4CCA and 4BCA form a commutable group of crystal structures, which may be realized experimentally or computationally, and constitute the landscape. Unlike the results obtained by Kitaigorodskii, all but two of the multiple solid solutions obtained in the methyl‐doping experiments take structures that are different from the hitherto observed crystal forms of the parent compounds. Even granted that the latter might be inherently polymorphic, this unusual observation provokes the suggestion that solid solution formation may be used to probe the crystal structure landscape. The influence of π⋅⋅⋅π interactions, weak hydrogen bonds and halogen bonds in directing the formation of these new structures is also seen.     

Ultrathin Ca‐PO4‐CO3 Solid‐Solution Nanowires: A Controllable Synthesis and Full‐Color Emission by Rare‐Earth Doping

It was found that calcium carbonate (CaCO₃) and hydroxyapatite (Ca₁₀(OH)₂(PO₄)₆), which are two crucial constituents of the most abundant minerals in nature and very important bioinorganic components in the tissues of mineralizing organisms, can form solid solutions in a wide range of PO₄^3?/CO₃^2? (P/C) ratios at low temperature when prepared as ultrathin nanowire structures. This is due to the special reactivity of ultrasmall nanocrystals, which can effectively lower the synthetic temperature and promote the formation of solid solutions. The as‐prepared ultrathin nanowires with suitable P/C ratios presented strong blue luminescence due to the existence of abundant defects strengthened by CO₃^2?. If used as the matrix, the as‐prepared ultrathin nanowires demonstrated bright green or red luminescent properties when doped with Tb³⁺ or Eu³⁺ ions, and simultaneously retained their original morphologies. These three kinds of fluorescent nanowires could reproduce a full range of luminescence colors based on additive color mixtures of the three primary colors (red, green, and blue). In addition, under the same reaction system, ultrafine rare‐earth‐doped (Ce³⁺, Tb³⁺, Eu³⁺) nanowires (about 1 nm in diameter) were synthesized by using a one‐step hydrothermal process, which further pushed the size of the Ca‐PO₄‐CO₃ nanobuilding blocks to one unit cell region. These ultrafine nanowires displayed excellent film‐forming properties and the ability to absorb UV radiation.     

Crystalline Behavior and Structure of a Liquid Crystal Compound, 5‐{[4′‐(((Pentyl)oxy)‐4‐biphenylyl)carbonyl]oxy}‐1‐pentyne

Single crystals of two liquid crystal compounds, 5‐{[4′‐(((pentyl)oxy)‐4‐biphenylyl)carbonyl]oxy}‐1‐pentyne (A3EO5) and 5‐{[(4′‐nonyloxy‐4‐biphenylyl)carbonyl]oxy}‐1‐pentyne (A3EO9), have been prepared by solution growth technique. The morphologies and structures of A3EO5 and A3EO9 crystals were investigated by wide angle X‐ray diffraction (WXRD), atom force microscope (AFM) and transmission electron microscope (TEM). In contrast to the same series of compounds which have a longer alkyl tail, 5‐{[(4′‐heptoxy‐4‐biphenylyl)carbonyl]oxy}‐1‐pentyne (A3EO7), 5‐{[(4′‐heptoxy‐4‐biphenylyl)oxy]carbonyl}‐1‐pentyne (A3E′O7) and A3EO9, A3EO5 shows strikingly different crystalline behavior. The former three compounds have only one crystal form, whereas A3EO5 exhibits polymorphism. Specifically, A3EO5 crystals grown from toluene solution show two crystal forms. The first one is crystal I which adopts a monoclinic P112/m space group with unit cell parameters of a?5.79 Å, b?8.34 Å, c?43.92 Å, γ?96°, and the other one is crystal II which adopts a monoclinic P112 space group with unit cell parameters of a?5.55 Å, b?7.38 Å, c?31.75 Å, γ?94°. When using dioxane as the solvent to grow A3EO5 crystal, we can selectively obtain crystal I. A3EO5 melt‐grown crystals also have two crystal forms which derive from crystal I and crystal II, respectively. The different crystalline behavior of the compounds should correlate with their different electron dipole moment resulting from the different length of alkyl tail.     

Crystal structures of the anhydrous and two solvated forms of methyl 4‐(4‐fluorophenyl)‐6‐methyl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate

Methyl 4‐(4‐fluorophenyl)‐6‐methyl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate, ( I ), was found to exhibit solvatomorphism. The compound was prepared using a classic Biginelli reaction under mild conditions, without using catalysts and in a solvent‐free environment. Single crystals of two solvatomorphs and one anhydrous form of ( I ) were obtained through various crystallization methods. The anhydrous form, C₁₃H₁₃FN₂O₃, was found to crystallize in the monoclinic space group C2/c. It showed one molecule in the asymmetric unit. The solvatomorph with included carbon tetrachloride, C₁₃H₁₃FN₂O₃·0.25CCl₄, was found to crystallize in the monoclinic space group P2/n. The asymmetric unit revealed two molecules of ( I ) and one disordered carbon tetrachloride solvent molecule that lies on a twofold axis. A solvatomorph including ethyl acetate, C₁₃H₁₃FN₂O₃·0.5C₄H₈O₂, was found to crystallize in the triclinic space group P with one molecule of ( I ) and one solvent molecule on an inversion centre in the asymmetric unit. The solvent molecules in the solvatomorphs were found to be disordered, with a unique case of crystallographically induced disorder in ( I ) crystallized with ethyl acetate. Hydrogen‐bonding interactions, for example, N—H…O=C, C—H…O=C, C—H…F and C—H…π, contribute to the crystal packing with the formation of a characteristic dimer through N—H…O=C interactions in all three forms. The solvatomorphs display additional interactions, such as C—F…N and C—Cl…π, which are responsible for their molecular arrangement. The thermal properties of the forms were analysed through differential scanning calorimetry (DSC), hot stage microscopy (HSM) and thermogravimetric analysis (TGA) experiments.     

Synthesis,Crystal Structure and Hydrolysis of a Novel Anhydrogalactosucrose: 2′‐Methoxyl‐O‐1′,4′:3′,6′‐dianhydro‐β‐D‐fructofuranosyl 3,6‐anhydro‐4‐chloro‐4‐deoxy‐α‐D‐galactopyranoside

A novel anhydrogalactosucrose derivative 2′‐methoxyl‐O‐1′,4′:3′,6′‐dianhydro‐β‐D‐fructofuranosyl 3,6‐anhydro‐4‐chloro‐4‐deoxy‐α‐D‐galactopyranoside ( 4 ) was prepared from 3,6:1′,4′:3′,6′‐trianhydro‐4‐chloro‐4‐deoxy‐galactosucrose ( 3 ) via a facile method and characterized by ¹H NMR, ¹³C NMR and 2D NMR spectra. The single crystal X‐ray diffraction analysis shows that the title molecule forms a two thee‐dimensional network structure by two kinds of hydrogen bond interactions [O(2) H(2)···O(7), O(5) H(5)···O(8)]. Its stability was investigated by acid hydrolysis reaction treated with sulfuric acid, together with the formation of 1,6‐Di‐O‐methoxy‐4‐chloro‐4‐deoxy‐β‐D‐galactopyranose ( 5 ) and 2,2‐Di‐C‐methoxy‐1,4:3,6‐dianhydromannitol ( 6 ). According to the result, the relative stability of the ether bonds in the structure is in the order: C(1) O C(5)≈C(3′) O C(6′)≈C(1′) O C(4′)>C(3) O C(6)≈C(1) O C(2′)>C(2′) O C(5′).     

Combinatorial Crystal Synthesis: Structural Landscape of Phloroglucinol:1,2‐bis(4‐pyridyl)ethylene and Phloroglucinol:Phenazine

A large number of crystal forms, polymorphs and pseudopolymorphs, have been isolated in the phloroglucinol‐dipyridylethylene (PGL:DPE) and phloroglucinol‐phenazine (PGL:PHE) systems. An understanding of the intermolecular interactions and synthon preferences in these binary systems enables one to design a ternary molecular solid that consists of PGL, PHE, and DPE, and also others where DPE is replaced by other heterocycles. Clean isolation of these ternary cocrystals demonstrates synthon amplification during crystallization. These results point to the lesser likelihood of polymorphism in multicomponent crystals compared to single‐component crystals. The appearance of several crystal forms during crystallization of a multicomponent system can be viewed as combinatorial crystal synthesis with synthon selection from a solution library. The resulting polymorphs and pseudopolymorphs that are obtained constitute a crystal structure landscape.     

Theoretical and Experimental Exploration of the Energy Landscape of the Quasi‐Binary Cesium Chloride/Lithium Chloride System

As a case study, the energy landscape of the cesium chloride/lithium chloride system was investigated by combining theoretical and experimental methods. Global optimization for many compositions of this quasi‐binary system gave candidates for possible modifications that constitute promising targets for subsequent syntheses based on solid‐state reactions. Owing to the synergetic and complementary nature of the computational and experimental approaches, a substantially better efficiency of exploration was achieved. Several new phases were found in this system, for the compositions CsLiCl₂ and CsLi₂Cl₃, and their thermodynamic ranking with respect to the already‐known phases was clarified. In particular, the new CsLiCl₂ modification was shown to be the low‐temperature phase, whilst the already‐known modification for this composition corresponded to a high‐temperature phase. Based on these results, an improved cesium chloride/lithium chloride phase diagram was derived, and this approach points the way to more rational and more efficient solid‐state synthesis.     

Synthesis,Crystal Structure,Spectroscopic, Electrochemical and Antimicrobial Properties of Cu(II) Complex with the Mixed Ligands of 2,9‐Dimethyl‐1,10‐phenanthroline and 4‐Hydroxypyridine‐2,6‐dicarboxylic Acid

A mononuclear Cu(II) complex with mixed ligands, formulated as [Cu(hypydc)(dmp)]·H₂O (hypydc=4‐hydroxypyridine‐2,6‐dicarboxylate, dmp=2,9‐dimethyl‐1,10‐phenanthroline), was synthesized and well characterized by single crystal X‐ray diffraction analysis, as well as spectroscopic (IR, UV‐Vis), and electrochemical methods. The Cu(II) atom exhibits a distorted square‐pyramidal geometry. Intermolecular O? H···O and C? H···O hydrogen bonds, π‐π stacking interactions and C? H···π interactions seem to be effective in the stabilization of the crystal structure. The complex was also evaluated for its antimicrobial activity using in vitro microdilution methods. Six standard bacteria and a strain of Candida albicans were used for the antimicrobial activities. There was a very strong activity against Candida albicans and significant activities against Enterococcus fecalis, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus, indicating important biological activities of the complex.     

4- (4,6-二甲基嘧啶-2-基)-3-硫代脲酸甲酯的合成晶体结构及量子化学研究

4-（4,6-Dimethylpyrimidin-2-yl）-3-thio-allophanic acid methyl ester was synthesized with mixing 2-amino-4,6- dimethylpyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray diffraction measurement were obtained by recrystallization from dimethylformamide at room temperature. The crystal belongs to monoclinic symmetry with space group C2/m, and crystal parameters of a= 1.7537（5） nm, b= 0.6759（2） nm, c=1.1148（3） nm, β=118.557（4）°, V=1.1605（6） nm^3, Z=4, De= 1.375 g/cm^3,μ=0.271 mm^-1, F（000）=504, and 1519 [1〉2σ（I）] observable independent reflections were used for the determination and refmement of the crystal structures with final R1 of 0.0372 and wR2 of 0.0992. The theoretical investigation of the title compound was carried out with DRT-B3LYP/6-311G, HF/6-311G and MP2/6-311G methods, and the atomic net charges and the population were discussed.     

具有U构型的二{1-甲硫基-1-[1-苯基-1-(1-苯基-3-甲基-5-氧代-4,5二氢吡唑-4-烯)-甲氨基]亚氨甲基}二硫醚的晶体结构

The reaction of 1-phenyl-3-methyl-4-benzoyl-2,5-dihydro-1H-pyrazol-5-one (PMBP) and methyldithiocarbazate (mdtc) in methanol results in formation of a yellow crystalline solid, adduct of 1-phenyl-3-methyl-4benzoyl-2,5-dihydro-lH-pyrazol-5-one and methyldithiocarbazate. When the yellow solids were dissolved in a mixture of methanol and ether (1:4), a red crystal, which is an oxidation product of the former, was obtained by allowing solvent to evaporate for a few days at room temperature. The X-ray analysis of the red crystal indicates that it is a novel disulfide with a special structure like a “U” conformation in the solid state.     

Nitrogen-rich 6-（3,5-Dimethylpyrazol-1-yl）-3-（2,4,6-trinitroanilino）-1,2,4,5-tetrazin： Synthesis, Crystal Structure and Thermal Property

6-（3,5-Dimethylpyrazol-1-yl）-3-（2,4,6-trinitroanilino）-1,2,4,5-tetrazin （1） has been synthesized and characterized by ^1H NMR, MS, elemental analysis, infrared spectra and thermal analyses. The crystal structure was determined by X-ray diffraction method. 1 is crystallized in P21/c space group of monoclinic crystal system, and exhibits good physical properties, such as high densities （〉 1.55 g·cm^-3） and good thermal stabilities （Td〉220 ℃）. The intrermolecular hydrogen bonds construct the P- and M-helices from organic molecules and may contribute to the high melting points.     

Crystal structure and photoreactivity of a halogen‐bonded cocrystal based upon 1,2‐diiodoperchlorobenzene and 1,2‐bis(pyridin‐4‐yl)ethylene

The formation of a photoreactive cocrystal based upon 1,2‐diiodoperchlorobenzene ( 1,2‐C₆I₂Cl₄ ) and trans‐1,2‐bis(pyridin‐4‐yl)ethylene ( BPE ) has been achieved. The resulting cocrystal, 2( 1,2‐C₆I₂Cl₄ )·( BPE ) or C₆Cl₄I₂·0.5C₁₂H₁₀N₂, comprises planar sheets of the components held together by the combination of I…N halogen bonds and halogen–halogen contacts. Notably, the 1,2‐C₆I₂Cl₄ molecules π‐stack in a homogeneous and face‐to‐face orientation that results in an infinite column of the halogen‐bond donor. As a consequence of this stacking arrangement and I…N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid‐state [2 + 2] cycloaddition reaction that produces rctt‐tetrakis(pyridin‐4‐yl)cyclobutane ( TPCB ) with an overall yield of 89%. A solvent‐free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield.     

Structure and Photochemical Properties of r‐1, c‐2, t‐3, t‐4‐l, 3‐Bis [2‐ (5‐R‐benzoxazolyl) ] −2,4‐di (4‐R' ‐phenyl) cyclobutane

r‐1, c‐2, t‐3, t‐4‐1,3‐Bis[2‐(5‐R‐benzoxazolyl)]‐2,4‐di(4‐R'‐phenyl)cyclobutane (IIa: R=R' = H; IIb: R=Me, R'= H; IIc: R = Me, R' = OMe) was synthesized with high stereo‐selectivity by the photodimerization of trans‐l‐[2‐(5‐R‐benzoxazolyl)]‐2‐(4‐R'‐phenyl) ethene (Ia: R=R' = H; Ib: R = Me, R' = H; Ic: R = Me, R' = OMe) in sulfuric acid. The structures of IIa–IIc were identified by elemental analysis, IR, UV, ¹H NMR, ¹³C NMR and MS. The molecular and crystal structure of IIc has been determined by X‐ray diffraction method. The crystal of IIc (C₃₄H₃₀N₂O₄. 0.5C₂OH) is monoclinic, space group P2₁/n with cell dimensions of a = 1.5416(3), b =0.5625(1), c = 1.7875(4) nm, β = 91.56 (3)°, V= 1.550(1) nm³, Z = 2. The structure shows that the molecule of IIc is centrosymmetric, which indicates that the dimerization process is a head‐to‐tail fashion. The selectivity of the photodimerization of Ia–Ic has been enhanced by using acidic solvent and the reaction speed would be decreased when electron donating group was introduced in the 4‐position of the phenyl group. That the photodimerization is not affected by the presence of oxygen as well as its high stereo‐selectivity demonstrated that the reaction proceeded through an excited singlet state. It was also found that under irradiation of short wavelength UV, these dimers underwent photolysis completely to reproduce its trans‐monomers, and then the new formed species changed into their cis‐isomers through trans‐cis isomerization.     

Synthesis, Reactivity and Crystal Structure of β—Diketiminate Ytterbium Chlorides

Reaction of anhydrous YbCl3 with 1 equiv, of LLi [L=p-ClPhNC(Me)CH(Me)N(C6H3-2,6-i-Pr2)] in THF at room temperature gave the β-diketiminate lanthanide dichloride LYbCl2(THF)2 (1) in good isolated yield. Similarly reaction of anhydrous YbCl3 with 1 equiv, of LLi, then with 1 equiv, of t-BuCpNa in THF yielded the expected mixed-ligand β-diketiminate ytterbium chloride (t-BuCp)YbL(μ-Cl)2Li(THF)2 (2). Both 1 and 2 were well characterized by elemental analysis, IR spectra, ^1H NMR spectra, and X-ray diffraction analysis.     

Crystallographic report: Chloro(N,N‐diethyldithiocarbamato)(4,7‐dimethyl‐1, 10‐phenanthroline)mercury(II) hemi‐chloroform solvate

The X‐ray crystal structure of Hg(S₂CNEt₂)(4,7‐Me₂‐phen)Cl features an essentially four‐coordinate geometry for mercury within a ClN₂S donor set that defines a distorted tetrahedral arrangement. Copyright © 2003 John Wiley & Sons, Ltd.     

Spiral‐Type Heteropolyhedral Coordination Network Based on Single‐Crystal LiSrPO4: Implications for Luminescent Materials

Novel structures of luminescent materials, which are used as light sources for next‐generation illumination, are continuously being improved for use in white‐light‐emitting diodes. Activator‐doped known structures are reported as habitual down‐conversion phosphors in solid‐state lightings and displays. Consequently, the intrinsic qualities of the existent compounds produce deficiencies that limit their applications. Herein we report a spiral‐network single‐crystal orthophosphate (LiSrPO₄) prepared in a platinum crucible with LiCl flux through crystal‐growth reactions of SrCl₂ and Li₃PO₄ in air. It crystallizes in a hexagonal system with a=5.0040(2) and c=24.6320(16) Å, V=534.15(5) ų, and Z=6 in the space group P6₅. The unit cell is comprised of LiO₄ and PO₄ tetrahedrons that form a three‐dimensional LiPO₄^2? anionic framework with a helical channel structure along the c axis in which the Sr²⁺ cation is accommodated. The optical band gap of this composition is about 3.65 eV, as determined by using UV/Vis absorption and diffuse reflection spectra. We used the crystal‐growth method to synthesize blue‐ and red‐emitting crystals that exhibited pure color, low reabsorption, a large Stokes shift, and efficient conversion of ultraviolet excitation light into visible light. Emphasis was placed on the development of gratifying structure‐related properties of rare‐earth luminescent materials and their applications.     

4‐Naphthylmethyl Proline Forms a Channel Structure

Proline and proline derivatives are useful tools to control the structural properties of peptides and proteins, and thereby modulate numerous processes. Here, we show that proline derivatives can have unique structural properties in the solid state by presenting the crystal structure of zwitterionic (2S,4S)/(2S,4R)‐4‐[(naphthalen‐2‐yl)methyl]proline (H‐Nap‐OH). This amphiphilic proline derivative forms a columnar structure around large hydrophilic and small hydrophobic channels with diameters of 9 Å and 4 Å, respectively. We show that this architecture, which is unprecedented for amino acids, results from the combination of a hydrogen bond network between the ammonium and carboxylate moieties and π–π as well as CH–π interactions between the aromatic moieties.     

三硝基间苯三酚1,5-二氨基四唑盐的制备、晶体结构及热分析

通过1,5-二氨基-1,2,3,4-四唑（DAT）与等摩尔的2,4,6-三硝基-1,3,5-苯三酚（TNPG）反应,制备了新型离子型含能化合物DATH⁺TNPG^-。通过X射线单晶衍射、元素分析、FT-IR光谱和¹H NMR对其进行了表征。晶体结构测试表明：该化合物的晶体属于单斜晶系,P2(1)/c空间群,a = 1.3399(3),b= 0.47088(9),c = 2.0127(4) nm,β= 92.83(3) ^o,V = 1.2684(4) nm³, Z= 4。在氢键、静电引力和范德华力的作用下该化合物形成了稳定的三维网状结构。对DAT和DATH⁺TNPG^-晶体进行了DFT-B3LYP/6-31G**周期性计算研究,得到其Mulliken电荷分布和重叠布居,从理论上说明DAT质子化位置是在四唑环的N(4)原子。采用TG-DTG和DSC技术对目标化合物的热分解进行了研究,并采用Kissinger和Ozawa-Doyle法对热分解过程的非等温反应动力学进行了计算。